1. Field of the Invention
The present invention relates to an airbag apparatus mountable on a vehicle that includes an inflatable airbag and an inflator that supplies inflation gas to the airbag. More particularly, the invention relates to an airbag apparatus suitable for use as a knee-protecting or a side impact airbag apparatus in which an inflator is put through an insert hole of an airbag such that a first end of the inflator is located outside of the airbag whereas a second end of the inflator having gas discharge ports is housed inside the airbag.
2. Description of Related Art
In a knee-protecting or a side impact airbag apparatus, an airbag is secured to an installation location at its portion dislocated from an insert hole for receiving an inflator. In this kind of airbag apparatus, it is inevitable that a tensile force acts on a peripheral area of the insert hole which is positioned by an end of the inflator. Upon airbag deployment, since the inflator secured to the installation location positions the peripheral area of the insert hole, a portion of the peripheral area on the side of action direction of the tensile force is pulled and thereby causing a gap between the portion of the peripheral area on the side of the action direction of the tensile force and the outer circumference of the inflator. JP 2008-120290 discloses an airbag apparatus intended to solve the above problem. This airbag apparatus includes an airbag body provided with an insert hole and a flexible seal cloth applied to a peripheral area of the insert hole on an inner circumference of the bag body. The seal cloth includes on a location corresponding to the insert hole a fitting hole for receiving the inflator, and is provided with a slack on part of the peripheral area of the fitting hole on which a tensile force acts upon airbag deployment so that gas seal is secured at the periphery of the insert hole of the bag body.
However, this configuration that the slack of the seal cloth is formed only on the side of the peripheral area of the fitting hole on which a tensile force acts can fail to deal with such an event that the direction of action of the tensile force varies during airbag deployment, for instance orthogonally. In such an event, a gap can still be formed between the inner circumference of the insert hole and the outer circumference of the inflator. Therefore, it is desired to further improve gas seal of the periphery of the insert hole.